hint on OO

[mickey]

HI, I have mainform class that has got a member object WIDGETGL; widgetGL show some GL objects that are members of StructureGL; there's only one instance of StructureGL (ok); I declared it as global variabile inside mainform.ui.h; in others part of app that StructureGL is request I used extern declaration...

//mainform.ui.h
StructureGL strutGL;

//mainform.ui.h
StructureGL strutGL;

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//WIDGETGL.cpp
extern StructureGL strutGL;
void WIDGETG::paintGL()
    structGL.drawSPhere();

//WIDGETGL.cpp
extern StructureGL strutGL;
void WIDGETG::paintGL()
    structGL.drawSPhere();

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the question: can it be ok? Is it better declare strutGL as member of mainform class? or what? thanks...

[high_flyer]

In general globals in C++ are bad practice (seldom they are really needed)
Is there anything preventing you from making something like:

//define in widgetg.h: StructureGL m_structGL;
void WIDGETG::setStructure(const StructureGL &strutGL)
{
  m_structGL = structGL;
}

//define in widgetg.h: StructureGL m_structGL;
void WIDGETG::setStructure(const StructureGL &strutGL)
{
  m_structGL = structGL;
}

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[mickey]

is make strutGL member of MainForm class a bad idea? mainform must use strutGL....

[high_flyer]

Could you elaborate on the problem you have?
What it is you want to do, and what are the alternatives you are considering to acheive it?

[mickey]

mainform class need to use that structGL and widgetGL too; I wonder if an instance of structGL as member of mainform class is likely...you just said avoid global variabiles.....

[high_flyer]

What is the relationship between mainform and widgetGL?
Is one a member of the other?
Can one access the other?
Is there another object that sees them both?

[mickey]

What is the relationship between mainform and widgetGL?
Is one a member of the other?
Can one access the other?
Is there another object that sees them both?

widgetGL is member of MainForm; widgetGL can access to MainForm class and viceversa;
there isn't object that can see both them..

[high_flyer]

So what is the problem then?
If both classes need to access the same element, and one class is a member of the other then just make structGL member in MainForm and pass it to and from widgetGL the way I showed in the beginning.